Stripping Tub Paint and Other Body Work Qs

Hey guys-

i dont know if this is really the correct forum, so if it isnt, would the moderators kindly move it?

my rotisserie is 1/2 complete and i hope to have the tub mounted onto it in the next week or so to start the body work...

whats the best MECHANICAL method of stripping the old paint? the outside of the tub is grey primer (PO) and the inside is the golden eagle brown..

also, i have some small/medium pin holes in the floor, and one option is the copper spoon and plug method... and/or the use of kitty hair body filler...

any suggestions as to which method is better?

is chemical BETTER than mechanical?

if you need pix, it ll be a few days until i can get the tub out of its current position and into decent light... just trying to have a game plan

thanks everyone!

 

As far as welding or bondo, weld. Removing paint, sand, wire wheel, paint stripper, those plastic things that you put in a drill motor. Tried them all, went back and fourth between them all. That said. If the paint and body are solid why remove the paint? Just sand till smooth and re paint.

 

i would weld up the holes. for the larger ones you should make a filler patch if the hole if bigger than 3/8". a duel action sander works well on the flat large surfaces. i small 2" angle air grinder with a scotch brite pad works for the smaller spots. i would try aircraft paint stripper first. put it on thick and let it sit then after the paint bubbles scrap it off with a paint scraper and wire brush. reappy the stripper as needed. i like the chemical method since the mecanical methods throw sanding dust all over the place. with the aircraft stripper i can just sweep up the old paint flakes off the ground.

 

Here's what I would do. The usual approach is to leave the existing paint in place if it is well adhered. Sand to bare metal any places where the paint is lifting or where you have rust. Weld up your holes. Sand the surface of the old paint for adhesion - a gray or red scotchbright is good for this. Then spray everything with a good epoxy primer. Follow up with your filler and 2K filler/primer as needed, then top coat. If you let the epoxy cure for more than a week or so, you'll need to scuff it for adhesion before you paint over it.

Do you have a problem with chemical stripping? If I wanted bare metal, I'd probably go with the aircraft stripper.

There are lots of ways to do this, but I think everyone will agree that welding is better than any filler.

 

I've used 3 mechanical methods to remove paint/primer to bare metal:

1. Sand blast
2. Grinder with a wire wheel and wire cup
3. Dual action sander with high grit...i.e. ~60 grit

I bought a Harbor Freight grinder (Chicago Electric) for about $17 on sale. Got the wheel and cup there too. You can also by the 3M paint remover wheels for drills if you need slower speed or more control.

I also welded every hole that I could see...then used the same grinder with a flap disk to smooth out the metal (or grinder wheel if it's a lot). I only used the body filler to help form a corner or smooth out a section.

I stayed away from any chemical paint remover...except small parts that I could soak with laquer thinner in a coffee can.

 

i dont have a problem with chemical stripper other then limited space, proximity to the house (fumes and dogs), and the fact i have never actually uused it before...

the tub looks pretty darn good actually, and i have a DA sander that i paid ZERO dollars for... i also have 2-3 angle grinders with cup brushes and flap disks... i dont think it will need to go down to bare steel except in the obvious places... rust and/or welding...

@ timgr what IS a good epoxy primer? i dont think i have ever seen one in a rattle can that i am aware of... and i dont know what 2K filler/primer is either... could you please elaborate?

i do NOT have REAL spraying capabilities (i only have the 26 gal craftsman compressor) so rattle cans will have to suffice until i can get it assembled and to the body shop... so ANY thoughts/suggestions on simple/crude methods would be great... just to keep flash rust at bay until i can get it done

thanks guys, for all the info!

 

You probably won't see a good epoxy in a rattle can unless a paint shop can mix it into the can for you. I used Southern Polyurethane's product which is a 2 part epoxy primer. It's like shrink wrapping the metal, very tough material. The issue is that most times you should plan on painting relatively quickly (within days is ideal) after spraying. You can wait, but you will likely have to scuff the surface and possibly apply more primer before painting. The 2K is a regular type of 2 part primer that is a bit heavier so it helps fill and smooth out small imperfections.

FWIW, I also have a small compressor and never painted before. It can work if you take your time and read up on techniques, etc. I had some help from the guys at North Georgia Collision supply in Woodstock.

Edited to add:
One word of warning...the 2 part primers/paints have isocyanates in them, you have to make sure to get good safety equipment such as respirator and goggles. I used a non-forced air respirator that was appropriately rated and changed the filters often.

 

My Jeep had several layers of old paint on it I wanted to remove. I tried various mechanical methods of paint stripping with limited success. I finally bit the bullet & paid a local shop to blast it with plastic media. It came out GREAT-all the sheetmetal looked like brand new, and it was nice & smooth, unlike the rough surface you get from sandblasting. Note that the media blasting wont remove bondo or heavy surface rust-my hood had surface rust & had to be sandblasted.

 

Thanks everyone!

PM sent Norm

maybe i ll swing by sherrys body shop and talk to their paint guy about it some... see what i need and stuff... in fact, i think thats where they (towne lake collision) gets their materials... i ll start with the grille and the dash and see what kind of results i get

 

Yes, epoxy primer is a 2-part concoction. You don't have to spray it - you can roll it on or brush, though it won't be as smooth. Even an airless sprayer would work. I too use the Southern Polyurethane's primer - it's said to be one of the best. There are cheaper epoxy primers available; my understanding is that the difference is mostly in the amount of solids that the primer contains. You can thin the primer with a high quality reducer (again SPI) to the consistency you want.

For bare metal, you have two choices: epoxy primer or etch primer. Most body shops will use etch, because it's fast. Amateurs and other builders typically use epoxy. Both are good - pick the one that sounds best to you. You can apply filler directly to metal or to fresh epoxy, if you wish. I recall you cannot put filler over etch... but I don't use it, so check the manufacturer's instructions.

There are lots of different primers and filler/primers that can go over your base. They will fill any pits and scratches better than epoxy. But epoxy is tough, way tough.

None of this stuff will last if it's applied over rusty metal. You can try the various rust treatments and paint over it, but you are taking your chances.

Pretty sure epoxy does not contain isocyanates - but all your 2-part top coat formulations will. In any case, you don't want any contact with any of this stuff when liquid. Use a respirator, wear a bunny suit, goggles... use gloves for everything. You're going to go through a lot of gloves.

 

i was originally thinking that this gun would work

Wagner HVLP Conversion Gun



but according to the specs for pushing it, i dont have enough OOMPH in my compressor...

according to the label on my



i only get 6.3 scfm @ 40psi and 4.9 scfm @ 90psi

am i out of luck?

i would REALLY like to shoot this myself, but if i cant, then so be it... just trying to save some $ as i have yet another JEEP to do in the future... cost of a spray gun vs the cost of 2 trips to the body shop

 

HVLP takes more air than a conventional "old fashioned" spray gun. The HVLP guns are nice because you lose less material in overspray. Something like this http://www.spraygunworld.com/products/Astro/Astro Pneumatic - 4008.htm might be more suitable. You can use your compressor, but you won't be able to work as fast - you'll need to wait for the compressor to catch up with your air usage.

The experts on this stuff hang out at the autobody 101 forum www.autobody101.com

 

cool... thanks timgr :tea:

will i need a drier and all that associated gobbledygook?

 

You can go check out the products at southernpolyurethanes.com they also have some good information that's worth reading. The MSDS sheets are there too so you can see what nasties are in the stuff that you're going to use.

 

You mean water separator? I would get one and mount it to the compressor. I use this http://www.tptools.com/p/65,110_1and2-Standard-Water-Separator.html with a Harbor Freight regulator http://www.harborfreight.com/industrial-air-filter-regulator-68247.html I was using the filter/separator that came with the regulator. I took it apart to clean it, and it would not seal air-tight again.

I expect you can use the regulator and hose that came with the compressor.

 

The OP Matt (Texas Blues) asked me a few questions by PM, and I'm going to post most of my answer here, so everybody can read it.

Here's my water separator and regulator:



So this is the water separator and regulator that I linked above. The regulator and WS have been connected with standard black iron pipe fittings. These are available at your local big box home center (ie Home Depot or Lowes). You just put together what you need to connect the pieces together. Use some pipe dope and voila: plumbing. I know that HD has air fittings too (ie quick connects) - make sure you get the air fittings that match your other equipment - take along a sample to match. If you want to mount the water separator on the wall, and connect the tank-mounted regulator to that, you can. Just put together quick connects and pipe fittings to make it work.

There's a gate valve at the bottom of the pipe going out the bottom of the picture. These are available at the big box store too. The rest of my plumbing follows the plan described by TP Tools: www.tptools.com/pl/Images,metal_pipe_kits_L,74,2035_Modular-Metal-Piping-Kits.html I have a stationary compressor, so I have a gate valve at the compressor and a flex coupling there. The rest follows the plan provided by TP Tools. I have the orange part coming off of the compressor, and the green part is shown in the picture above.

All the black iron pipe I used is standard lengths, and came threaded. So it's just a matter of putting together the standard pieces. If you need a custom length, the big box store will cut and thread it for you. The main advantage to the black iron pipe is cooler air. This will make the water condense and separate, so it won't get to your paint gun. But you may not need all that pipe - put it all together with hose, and see how it works. A lot will depend on how humid it is where you are, and what the temperature is.

 

the epoxy is just as bad for you as any 2k product...if you have more than 2 paint jobs on the tub strip it. as the paint film gets thicker all kinds of strange things happen(cracking crazing generally bad things) think of it this way any "soft" layer (laquer,red lead,green putty basically any non hardened air dry product) will have a bad effect on the long term life of the paint.

 

thanks timgr! i didnt want to keep pounding this thread with goofy questions that maybe everyone knew the answer to mehh

anyway... i like the way you have yours set up... i WISH i had that kind of dedicated space... everything i have is portable, so it looks like i ll be sitting int he floor at the HD putting all this stuff together...

thanks SO much for the pic!

@ sterclan... i ll look at how many layers there are, i dont think theres more than the primer (from the PO) over the original golden eagle brown... thanks for the tip!

 

Re sterclan's comment - I looked at the MSDS for epoxy and there's no isocyanate listed; just solvents. The other 2K products like clearcoat list solvents and diisocyanate specifically. The isocyanates are a separate poisonous compound that is included to in 2K products to promote hardening.

Remember Bhopal?

Sterclan is right that spraying the epoxy products are a risk to your health if you do not use a proper respirator. The MSDS gives the same health warning for both epoxy and other 2K products. I'm not sure why this is - maybe it's just CYA wording. But I believe the chemistry is different, and does not involve isocyanates.

 

FYi Matt, you can buy respirators at HF that are rated for organic compounds. I think they run about $18.